Art Cashin says he can't figure out why the stock market's rebound Tuesday is so "tepid."

Cashin, UBS' director of floor operations at the NYSE, told CNBC's Bob Pisani at midday that bond yields are down and "we're very, very heavily oversold by a lot of metrics in the market" but stocks aren't responding with strong gains. "You really think this thing should break out."

The benchmark S&P 500 stock index is in a "very critical" level, he said. "The area around 1,655 to 1,657 is the top of a little down channel. If they can break out of there, maybe they can get a little credibility."

For now, "save the party hats," Cashin said. "We're not ready for them quite yet."